Fissette is the former coach of fellow Belgian Kim Clijsters and Simona Halep.
The former world No. 1 has been practicing with Fissette for the past week and says it is working out very well.
Sumyk, who worked with Azarenka for five years, is now coaching Eugenie Bouchard.
Azarenka's friend and agent, Meilen Tu—a former player and the wife of Sumyk—says that Victoria is excited to be with Fissette.
"After five great years with her former coach Sam Sumyk, he has decided to move on and she wishes him well," Tu said.
"Vika is looking forward to a fresh start coming off of a year of injury and she is eager to focus on playing great tennis."
Azarenka struggled throughout an injury-filled 2014, during which she broke up with the singer Redfoo. She admits that she was depressed after he ended their relationship.